Okay, obviously some of the best Lifetime movies feature insane plot lines that would never actually happen in real life. They're basically hour-and-a-half long soap operas, complete with all the normal tropes of that genre, including murder, incest, and yes, of course, amnesia. As The Washington Post reported, "Lifetime's first-ever TV movie, Memories of Murder, premiered on July 31, 1990. It starred Nancy Allen as a wife and stepmom who hits her head, gets amnesia and conveniently can't remember why a psychopath wants to kill her family." 

But really, when you watch Lifetime movies as an adult, that whole amnesia thing starts to seem like a pretty convenient plot point rather than a rare disease, as it once did when you were a kid. Clearly there's a lot more amnesia that takes place in Lifetime movies than in the real world. But hey, forgetting your entire life and the people in it makes for a great drama, so who could blame the network for using this trope so often?